Our eyes need tears to stay healthy and comfortable. If your eyes do not produce enough tears, or the right type of tears, you might experience dry eye symptoms.

Dry eye disease can cause these symptoms:

  • Discomfort, irritation or itchiness
  • Soreness, redness or burning
  • Blurry vision, or a grittiness feeling, as though there is a foreign body or a scratchiness in the eyes
  • Interestingly, when dry eye disease occurs, our eyes also may try to overcompensate, so watery eyes are very often a symptom of dry eye disease too

How does dry eye disease occur?

When you blink, a thin layer of tears spreads over the eye. We call this the tear film. It keeps the eye’s surface smooth and clear. The tear film is important for good vision.

The tear film is made of three layers:

  • An oily layer
  • A watery layer
  • A mucus layer

Each layer of the tear film serves a purpose:

  • The oily layer is on the outside of the tear film. It makes the tear surface smooth, and keeps tears from drying up too quickly. This layer is made in the eye’s meibomian glands.
  • The watery layer is in the middle, and makes up most of what we see as tears. We think that this layer cleans the eye, washing away particles that do not belong in the eye, and also has lots of dissolved nutrients. This layer comes from the lacrimal glands in the eyelids.
  • The mucus layer is the layer of the tear film that touches the cornea. Think of this mucus layer almost like the seaweed or coral layer on the bottom of the coral reef in the ocean, it helps anchor the rest of the tear film on the top of it. The mucus layer helps to spread the watery layer over the eye’s surface evenly, to keep the rest of the eye moist. Without mucus, tears would not stick to the eye.

Normally, our eyes constantly make tears to stay moist. If our eyes are irritated, or we cry, our eyes make a lot of tears. If there is a problem with any of the layers of the tear film, we end up with dry eyes.

Dry eye disease can escalate to be very uncomfortable, or may cause pain if it is left to become severe, so if you experience these symptoms, it is important to get them assessed by an optometrist to ensure that your eye condition is well managed.